Digital technology has enabled manufacturers of CD players to provide a so-called random play mode in which CD selections are played in varying non-sequential order. One approach, for example, uses a uniform random number generator such as a free running timer to generate numbers from which choice of the next selection may be determined. However, this approach allows unlimited repetition of selections before all selections have been played, a characteristic disliked by many CD player users, and does not allow users to replay any number of past selections or skip to as yet unplayed selections without loss of the current sequence, a feature sought by many CD player users.
Another approach that plays CD selections in varying non-sequential order is a variant of the preceding approach in which a number generator and memory array is employed to memorialize "played" selections, eliminating selection repetition. But once again, users may not move through the selection sequence.
CD players have allowed random choice and play of selections without repetitions (before playing of all other selections), and user chosen selection replays and skips where a complete selection sequence has been stored in memory and an index used to identify current selection. Inasmuch as a single CD may have up to ninety-nine selections (on individual "tracks"), and CD changers provided with up to twelve or more discs, the amount of memory and execution time required to implement this approach is significant and prohibitive.